CWE-799 Class Incomplete

Improper Control of Interaction Frequency

This vulnerability occurs when an application fails to properly restrict how often or how many times a user or automated system can interact with it.

Definition

What is CWE-799?

This vulnerability occurs when an application fails to properly restrict how often or how many times a user or automated system can interact with it.
Without proper frequency limits, both human users and automated bots can perform actions far more often than intended. This flaw is commonly exploited to launch denial-of-service (DoS) attacks, bypass business logic (like voting systems or promotional offers), or brute-force credentials by making unlimited password attempts. Developers must implement controls like rate limiting, request throttling, and CAPTCHAs to enforce interaction boundaries. These measures are essential for protecting system availability, ensuring fair use, and preventing automated tools from exploiting core application functions.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-799

  • CVE-2002-1876

    Mail server allows attackers to prevent other users from accessing mail by sending large number of rapid requests.

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

  1. 1

    Identifiziere einen Codepfad, der nicht vertrauenswürdige Eingaben ohne Validierung verarbeitet.

  2. 2

    Erzeuge eine Payload, die das unsichere Verhalten auslöst — Injection, Traversal, Overflow oder Logik-Missbrauch.

  3. 3

    Liefere die Payload über einen normalen Request aus und beobachte die Reaktion der Anwendung.

  4. 4

    Iteriere, bis die Antwort Daten preisgibt, Angreifer-Code ausführt oder Berechtigungen eskaliert.

Verwundbares Codebeispiel

Vulnerable C

In the following code a username and password is read from a socket and an attempt is made to authenticate the username and password. The code will continuously checked the socket for a username and password until it has been authenticated.

Verwundbar C 
char username[USERNAME_SIZE];
  char password[PASSWORD_SIZE];
  while (isValidUser == 0) {
  		if (getNextMessage(socket, username, USERNAME_SIZE) > 0) {
  			if (getNextMessage(socket, password, PASSWORD_SIZE) > 0) {
  				isValidUser = AuthenticateUser(username, password);
  			}
  		}
  }
  return(SUCCESS);
Sicheres Codebeispiel

Secure C

This code does not place any restriction on the number of authentication attempts made. There should be a limit on the number of authentication attempts made to prevent brute force attacks as in the following example code.

Sicher C 
int count = 0;
  while ((isValidUser == 0) && (count < MAX_ATTEMPTS)) {
  		if (getNextMessage(socket, username, USERNAME_SIZE) > 0) {
  			if (getNextMessage(socket, password, PASSWORD_SIZE) > 0) {
  				isValidUser = AuthenticateUser(username, password);
  			}
  		}
  		count++;
  }
  if (isValidUser) {
  	return(SUCCESS);
  }
  else {
  	return(FAIL);
  }
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Präventions-Checkliste

How to prevent CWE-799

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Erkennungssignale

How to detect CWE-799

SAST High

Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.

DAST Moderate

Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.

Runtime Moderate

Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.

Code review Moderate

Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.

Plexicus Auto-Fix

Plexicus erkennt CWE-799 automatisch und öffnet in unter 60 Sekunden einen Fix-PR.

Codex Remedium scannt jeden Commit, identifiziert genau diese Schwachstelle und liefert einen reviewer-ready Pull Request mit dem Patch. Keine Tickets. Keine Hand-offs.

Demo anfordern Plexicus kostenlos testen
Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-799?

This vulnerability occurs when an application fails to properly restrict how often or how many times a user or automated system can interact with it.

Wie gravierend ist CWE-799?

MITRE hat für diese Schwachstelle keine Exploit-Wahrscheinlichkeit veröffentlicht. Behandle sie als mittlere Auswirkung, bis dein Threat Model anderes belegt.

Welche Sprachen oder Plattformen sind von CWE-799 betroffen?

MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.

Wie kann ich CWE-799 verhindern?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

Wie erkennt und behebt Plexicus CWE-799?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-799 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.

Wo erfahre ich mehr über CWE-799?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/799.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-799

CWE-691 Parent

Insufficient Control Flow Management

This vulnerability occurs when a program's execution flow isn't properly managed, allowing attackers to bypass critical checks, trigger…

CWE-1265 Sibling

Unintended Reentrant Invocation of Non-reentrant Code Via Nested Calls

This vulnerability occurs when a non-reentrant function is called, and during its execution, another call is triggered that unexpectedly…

CWE-1281 Sibling

Sequence of Processor Instructions Leads to Unexpected Behavior

Certain sequences of valid and invalid processor instructions can cause the CPU to lock up or behave unpredictably, often requiring a hard…

CWE-362 Sibling

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

A race condition occurs when multiple processes or threads access a shared resource simultaneously without proper coordination, creating a…

CWE-430 Sibling

Deployment of Wrong Handler

This vulnerability occurs when a system incorrectly assigns or routes an object to the wrong processing component.

CWE-431 Sibling

Missing Handler

This vulnerability occurs when a software component lacks the necessary code to properly handle an error or unexpected event.

CWE-662 Sibling

Improper Synchronization

This vulnerability occurs when a multi-threaded or multi-process application allows shared resources to be accessed by multiple threads or…

CWE-670 Sibling

Always-Incorrect Control Flow Implementation

This weakness occurs when a section of code is structured in a way that always executes incorrectly, regardless of input or conditions.…

CWE-696 Sibling

Incorrect Behavior Order

This weakness occurs when a system executes multiple dependent actions in the wrong sequence, leading to unexpected and potentially…

Ressourcen

Further reading

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